by Daniel Fishman

Created on: December 13, 2006   Last Updated: July 18, 2009

By now you know that VPN stands for virtual private network. A VPN is a way to create a private network INSIDE a public network, using the same wires for transporting data.

Lets imagine that the internet is like the public roadway system, and the data is like people traveling on the roads. You can get from anywhere to anywhere else on the highway by getting in YOUR car and just driving out your driveway, getting on the road, and going wherever you want. You can visit public addresses at will, just by entering in a destination. You can go to any shopping mall, office complex or residence you want.

Once you get to that address, you can drive past and look in the windows all you want, and see everything on public display. Often however there is also a gate and a security guard that you'll have to sign in with to look drive around inside on their private roads, and the only way to get to these roads is through the gate. Sometimes the security guard wants a username and password. If you give it to him, he'll stick a tag in your windows (actually a cookie) that allows you to drive around in their private area. But eve with a cookie, there are some roads in the private area, that you will not be allowed to drive on. For those you have to be driving a company car, which you can only get from the company garage.

When you join a VPN, it's as if your driveway is blocked off, and a subway station opens up at your house. There's a guard outside the station, and when you want to get on, he inspects your credentials, and when they are in order he says "Right this way sir!" and lets you get on the subway, which transports you to the company garage INSIDE the company's private area. There you get a company car. You drive out of the garage in the company car, and of course you are already in your company's complex. Now you can go anywhere in the complex - for example, the email shop. The road to the email shop is backed up with all the delivery trucks trying to get in and each one has to be inspected very carefully for Spam, which takes a lot of time. But when the security guard sees that you are in a company car, he waives you around the line ("This way sir"), and you get to drive into the email shop right away.

Likewise there's a special radio in your car, so no matter where you go while in the company car (connected to the VPN) you are in touch with the office. They can get to you, and you can get to them via this radio. If someone sends you an email while you're in the company car, the dispatcher will tell you about it over the radio. If you want to know about the Johnson report, that's on the shared drive, you can can get it on the private fax machine that comes standard with the company car.

Of course if you wanted to you can drive out the front gate, and visit the rest of the internet in the company car. When you do this though, all people know about you is that you came from the company - they don't know anything else. No matter where you go on the internet/road, people will see that you're traveling in the company car/VPN. If you want to do some personal shopping you get out of the company car and walk around in the stores, and then they know it's you - but you get to the store and leave in the company car.

Obviously this is all just a metaphor, but I think it's a good explanation of the BASICS of a VPN.

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